Unmethylated Insulin DNA Is Elevated After Total Pancreatectomy With Islet Autotransplantation: Assessment of a Novel Beta Cell Marker.

Beta cell death may occur both after islet isolation and during infusion back into recipients undergoing total pancreatectomy with islet autotransplantation (TPIAT) for chronic pancreatitis. We measured the novel beta cell death marker unmethylated insulin (INS) DNA in TPIAT recipients before and immediately after islet infusion (n = 21) and again 90 days after TPIAT, concurrent with metabolic functional assessments (n = 25). As expected, INS DNA decreased after pancreatectomy (p = 0.0002). All TPIAT recipients had an elevated unmethylated INS DNA ratio in the first hours following islet infusion. In four samples (three patients), INS DNA was also assessed immediately after islet isolation and again before islet infusion to assess the impact of the isolation process: Unmethylated and methylated INS DNA fractions both increased over this interval, suggesting death of beta cells and exocrine tissue before islet infusion. Higher glucose excursion with mixed-meal tolerance testing was associated with persistently elevated INS DNA at day 90. In conclusion, we observed universal early elevations in the beta cell death marker INS DNA after TPIAT, with pronounced elevations in the islet supernatant before infusion, likely reflecting beta cell death induced by islet isolation. Persistent posttransplant elevation of INS DNA predicted greater hyperglycemia at 90 days.

Teplizumab treatment may improve C-peptide responses in participants with type 1 diabetes after the new-onset period: a randomised controlled trial.

AIMS/HYPOTHESIS: Type 1 diabetes results from a chronic autoimmune process continuing for years after presentation. We tested whether treatment with teplizumab (a Fc receptor non-binding anti-CD3 monoclonal antibody), after the new-onset period, affects the decline in C-peptide production in individuals with type 1 diabetes. METHODS: In a randomised placebo-controlled trial we treated 58 participants with type 1 diabetes for 4-12 months with teplizumab or placebo at four academic centres in the USA. A central randomisation centre used computer generated tables to allocate treatments. Investigators, patients, and caregivers were blinded to group assignment. The primary outcome was a comparison of C-peptide responses to a mixed meal after 1 year. We explored modification of treatment effects in subgroups of patients. RESULTS: Thirty-four and 29 subjects were randomized to the drug and placebo treated groups, respectively. Thirty-one and 27, respectively, were analysed. Although the primary outcome analysis showed a 21.7% higher C-peptide response in the teplizumab-treated group (0.45 vs 0.371; difference, 0.059 [95% CI 0.006, 0.115] nmol/l) (p = 0.03), when corrected for baseline imbalances in HbA(1c) levels, the C-peptide levels in the teplizumab-treated group were 17.7% higher (0.44 vs 0.378; difference, 0.049 [95% CI 0, 0.108] nmol/l, p = 0.09). A greater proportion of placebo-treated participants lost detectable C-peptide responses at 12 months (p = 0.03). The teplizumab group required less exogenous insulin (p < 0.001) but treatment differences in HbA(1c) levels were not observed. Teplizumab was well tolerated. A subgroup analysis showed that treatment benefits were larger in younger individuals and those with HbA(1c) <6.5% at entry. Clinical responders to teplizumab had an increase in circulating CD8 central memory cells 2 months after enrolment compared with non-responders. CONCLUSIONS/INTERPRETATIONS: This study suggests that deterioration in insulin secretion may be affected by immune therapy with teplizumab after the new-onset period but the magnitude of the effect is less than during the new-onset period. Our studies identify characteristics of patients most likely to respond to this immune therapy. TRIAL REGISTRATION: ClinicalTrials.gov NCT00378508 FUNDING: This work was supported by grants 2007-502, 2007-1059 and 2006-351 from the JDRF and grants R01 DK057846, P30 DK20495, UL1 RR024139, UL1RR025780, UL1 RR024131 and UL1 RR024134 from the NIH.

Relapsing and remitting severe hypoglycemia due to a monoclonal anti-insulin antibody heralding a case of multiple myeloma.

CONTEXT: We report a novel case of insulin autoimmune syndrome (IAS) presenting with hypoglycemia due to production of a monoclonal anti-insulin antibody in a patient subsequently found to have multiple myeloma (MM). OBJECTIVE: The aim of the study was to describe the 5-yr clinical course of a patient with IAS and MM and to characterize the origin and function of the pathogenic antibody. METHODS: We conducted a longitudinal case history with laboratory investigations to characterize the anti-insulin antibody subtype, specificity, affinity, and origin. RESULTS: The patient presented with IAS, which worsened during treatment of hepatitis C. The patient was then discovered to have a monoclonal gammopathy that progressed to MM. Treatment of the MM induced remission of the neoplasia and IAS, which then followed a synchronized course of progression and response to therapy. An anti-insulin IgG(3)-λ that bound specifically but with low affinity to the insulin B chain (amino acids 9-30) and that was distinct from the primary MM IgG(3)-κ clone was recovered from the patient and cloned. The antibody bound insulin and showed mutations of normal affinity maturation. CONCLUSIONS: We describe a case of MM heralded by IAS, where full characterization of the pathogenic antibody revealed that the monoclonal anti-insulin antibody had originated from a self-reactive clone.

Analysis of human biologics with a mouse skin transplant model in humanized mice.

Preclinical testing of human therapeutic monoclonal antibodies has been limited in murine models due to species differences in pharmacokinetics and biologic responses. To overcome these constraints we developed a murine skin transplant model in humanized mice and used it to test human monoclonal antibody therapy. Neonatal NOD/SCID/IL2Rγc(null) mice (NSG) were reconstituted with human CD34(+) hematopoietic stem cells (hNSG). When adult, these mice rejected MHC mismatched murine C57BL/6J skin grafts. Rejection required adequate reconstitution with human cells. There was diffuse infiltration of the epidermis and dermis with hCD8 and hCD4 cells in rejected grafts by immunohistochemistry. Studies with B6/MHC class I and II knockout mice donors indicated that neither is required for rejection. Graft rejection was associated with the development of effector and central memory T cells and an increase in serum immunoglobulins. We also tested the effects of teplizumab (anti-CD3 mAb) and found it could delay skin graft rejection, whereas ipilimumab (anti-CTLA-4 [cytotoxic T-lymphocyte antigen-4] mAb) treatment accelerated rejection. These findings demonstrate that hNSG mice reliably and predictably reject a xenogenic mouse skin graft by a human T cell mediated mechanism. The model can be utilized to investigate the ability of human immunotherapies to enhance or suppress functional human immune responses.

Blockade of RAGE suppresses alloimmune reactions in vitro and delays allograft rejection in murine heart transplantation.

The receptor for advanced glycation endproducts (RAGE), a multiligand member of the immunoglobulin superfamily, interacts with proinflammatory AGEs, the products of nonenzymatic glycation and oxidation of proteins; high-mobility group box 1 (HMGB1), also known as amphoterin and S100/calgranulins to amplify inflammation and tissue injury. Previous studies showed that blockade of RAGE suppressed recruitment of proinflammatory mechanisms in murine models. We tested the hypothesis that RAGE contributes to alloimmune responses and report that in vivo, acute rejection of fully allogeneic cardiac allografts in a murine model of heterotopic cardiac transplantation is significantly delayed by pharmacological antagonism of RAGE. In parallel, allogeneic T-cell proliferation in the mixed lymphocyte reaction is, at least in part, RAGE-dependent. These data provide the first insights into key roles for RAGE in allorecognition responses and suggest that antagonism of this receptor may exert beneficial effects in allogeneic organ transplantation.

The rise and fall of insulin secretion in type 1 diabetes mellitus.

An understanding of the natural history of beta cell responses is an essential prerequisite for interventional studies designed to prevent or treat type 1 diabetes. Here we review published data on changes in insulin responses in humans with type 1 diabetes. We also describe a new analysis of C-peptide responses in subjects who are at risk of type 1 diabetes and enrolled in the Diabetes Prevention Trial-1 (DPT-1). C-peptide responses to a mixed meal increase during childhood and through adolescence, but show no significant change during adult life; responses are lower in adults who progress to diabetes than in those who do not. The age-related increase in C-peptide responses may account for the higher levels of C-peptide observed in adults with newly diagnosed type 1 diabetes compared with those in children and adolescents. Based on these findings, we propose a revised model of the natural history of the disease, in which an age-related increase in functional beta cell responses before the onset of autoimmune beta cell damage is an important determinant of the clinical features of the disease.

Transplantation of the islets of Langerhans: new hope for treatment of type 1 diabetes mellitus.

For more than two decades, islet transplantation has been pursued as a curative treatment for type 1 diabetes mellitus (T1DM) with little success. It is likely that the failures of the past have involved technical difficulties in harvesting human islets, transplantation of insufficient amounts of islet tissue, the antagonistic effects of immune suppressive drugs, including calcineurin inhibitors and glucocorticoids, graft rejection and recurrent autoimmune disease. More recently, success has been reported in seven out of seven consecutive transplants using approaches that overcome the technical and therapeutic problems of the past. Although this success is noteworthy, issues remain that preclude the general application of islet transplants for treatment of the majority of patients with T1DM. These include the need for chronic immunosuppression and the requirement of large numbers of islets. Efforts are under way, using a variety of immunological, molecular and cellular strategies, to make this promising treatment available to the majority of patients with this disease.

Outbreak of Pasteurella pneumotropica in a closed colony of STOCK-Cd28(tm1Mak) mice.

Fifteen mice with Pasteurella pneumotropica orbital abscesses were noted in mice that were homozygous for a targeted Cd28 gene mutation. Only one mouse heterozygous for the Cd28 mutation was affected. According to phenotypic reactions and 16S rDNA sequencing, the isolates were most similar to biotype Heyl. This article provides evidence for an immunologic basis of susceptibility to P. pneumotropica infection. Fifteen mice with Pasteurella pneumotropica orbital abscesses were noted in mice that were homozygous for a targeted Cd28 gene mutation. Only one mouse heterozygous for the Cd28 mutation was affected. According to phenotypic reactions and 16S rDNA sequencing, the isolates were most similar to biotype Heyl. This article provides evidence for an immunologic basis of susceptibility to P. pneumotropica infection.

Regulation of C-C chemokine production by murine T cells by CD28/B7 costimulation.

C-C chemokines play an important role in recruitment of T lymphocytes to inflammatory sites. T lymphocytes secrete chemokines, but the activation requirements for chemokine production by T cells are uncertain. We studied the regulation of C-C chemokine production by CD28 costimulatory signals by murine T lymphocytes. Splenocytes from BALB/c mice cultured with anti-CD3 mAb expressed macrophage-inflammatory protein (MIP)-1alpha mRNA and secreted MIP-1alpha, which was inhibited by anti-B7-1 plus anti-B7-2 mAbs. MIP-1alpha production by Ag-stimulated T cells from DO.11.10 TCR transgenic mice was augmented by anti-CD28 mAb and increased compared with DO.11.10/CD28(-/-) cells. When T cell costimulation was provided by IL-2, MIP-1alpha was not enhanced. Studies with IL-2, IL-4, STAT4, and STAT6 knock-out mice suggested that chemokine production is controlled by pathways different from those regulating T cell differentiation. Thus, CD28 costimulation may amplify an immune response by stimulating T cell survival, proliferation, and production of chemokines that recruit T cells to inflammatory sites.

Expression and immune response to islet antigens following treatment with low doses of streptozotocin in H-2d mice.

Insulin dependent diabetes mellitus (IDDM) is likely to be due to the immunologic destruction of the islets of Langerhans. However, the relative importance of expression of a unique set of islet antigens or of differences in immune responses to those antigens in determining susceptibility to auto-immune diabetes is unknown. To a large extent, the reason for this uncertainty is the difficulty in directly identifying islet antigens expressed in vivo. We have studied the relationship between islet antigen expression, immune responsiveness to islet antigens, and the development of diabetes in diabetes induced by multiple low-doses of streptozotocin (STZ) in mice of the H-2d haplotype. We identified the expression of relevant islet antigens by testing the ability of STZ treated islets to induce tolerance to diabetes in C57BL/KsJ mice after intrathymic transplantation. C57BL/KsJ but not BALB/cByJ mice developed hyperglycaemia and insulitis following STZ treatment. Interferon-gamma transcription was detected in intrapancreatic lymphocytes from C57BL/KsJ mice but at lower levels in cell from BALB/cByJ. IL-4 levels were higher in BALB/cByJ than C57BL/KsJ. Intrathymic STZ-treated islets from syngeneic mice induced tolerance to diabetes in C57BL/KsJ mice following transient depletion of mature peripheral T cells, but islets from resistant BALB/cByJ mice did not induce tolerance to disease in C57BL/KsJ mice even though they did cause tolerance to the alloantigens. (C57BL/KsJ x BALB/cByJ)F1 mice developed hyperglycaemia like the susceptible parent following STZ treatment, and islets from these mice induced tolerance to MDSDM when treated with STZ and transplanted intrathymically into C57BL/KsJ. We conclude the expression of islet antigens and the intrapancreatic responses to STZ treated islets differs between mice that are susceptible and resistant to multi-dose streptozotocin induced diabetes mellitus.

CD28/B7 costimulation regulates autoimmune diabetes induced with multiple low doses of streptozotocin.

Insulin-dependent diabetes mellitus is believed to occur as a result of a T cell-mediated destruction of the islets of Langerhans. The factors that regulate the T cell responses, in particular the costimulatory signals required for the T cell activation, which result in islet cell destruction, are still unclear. CD28/B7 interactions have been shown to be important in the regulation of T cell immune responses. We, therefore, have examined the role of CD28/B7 interactions in a model of insulin-dependent diabetes mellitus in which T cell-dependent insulitis and hyperglycemia occur over a brief period, following multiple low doses of streptozotocin (multidose streptozotocin (STZ)-induced diabetes mellitus). Expression of CD28 was necessary for diabetes because CD28 -/- C57BL/KsJ animals developed neither hyperglycemia nor insulitis, and did not express IFN-gamma mRNA following STZ, unlike CD28 +/- C57BL/KsJ mice. The expression of B7-1 (CD80) and B7-2 (CD86) molecules was closely regulated during development of the disease. Expression of both CD80 and CD86 increased on cells in pancreatic lymph nodes in STZ-treated C57BL/KsJ mice. Expression of only CD86 increased on islet cells in diabetic mice. In wild-type animals, treatment with mAb against CD86 prevented, whereas treatment with mAb against CD80 exacerbated, insulitis and hyperglycemia, indicating that mAbs against these molecules differentially affect development of disease. We conclude that CD28 signal transduction is required for development of diabetes in multidose STZ-induced diabetes mellitus. CD80 and CD86 molecules, the CD28/CTLA4 ligands, may have different roles in regulation of the disease and affect T cell function at steps beyond differentiation into mature phenotypes.

CD28/B7 regulation of Th1 and Th2 subsets in the development of autoimmune diabetes.

CD28 ligation delivers a costimulatory signal important in T cell activation. This study demonstrates that the disruption of the CD28/B7 pathway early in the nonobese diabetic mouse strain, using CD28-/- and CTLA41g transgenic mice, promoted the development and progression of spontaneous autoimmune diabetes. Functional analyses of T cells isolated from CD28-deficient mice demonstrated that the GAD-specific T cells produced enhanced Th1-type cytokines (IL-2 and IFN gamma) and diminished Th2-type cytokine, IL-4. Moreover, there was a significant decrease in serum levels of anti-GAD antibodies of the IgG1 isotype consistent with a profound suppression of Th2-type responses in these animals. Thus, the early differentiation of naive diabetogenic T cells into the Th2 subset is dependent upon CD28 signaling and extends our understanding of the importance of Th1/Th2 balance in the regulation of this spontaneous autoimmune disease.

Regulation of cytokine production during development of autoimmune diabetes induced with multiple low doses of streptozotocin.

Cytokines have been shown to play an important role in regulating tolerance to islet Ags and provoking destructive islet lesions. However, data from a number of experimental systems have been conflicting, and the role of cytokines produced by T lymphocytes at various stages of diabetes has not been clearly defined. We have studied the production of cytokines in the pancreas during the development of autoimmune diabetes induced in mice by administration of (5) low doses of streptozotocin (STZ) (MDSDM). Diabetes in this model is T lymphocyte dependent. We used techniques of semiquantitative PCR to identify and quantitate cytokines that are produced. We have found that IL-2, IL-4, TNF-alpha, and IFN-gamma are expressed by the time the fourth dose of STZ is given. In the same pancreas, all of these cytokines (including IL-4) may be found. However, expression of IFN-gamma, but not IL-4, was limited to intrapancreatic lymphocytes and was not detectable at extrapancreatic lymphoid sites. Moreover, mAbs against IFN-gamma, but not against IL-4 or IL-2, prevent hyperglycemia and insulitis in MDSDM, suggesting that IFN-gamma regulates development of disease. Cells in the pancreases of nondiabetic mice treated with anti-IFN-gamma mAb and STZ show enhanced expression of IL-4, but the prevention of disease is due to blockade of the IFN-gamma itself, and not due to secretion of IL-4, because systemic administration of IL-4 does not prevent MDSDM. Thus, our findings indicate that cytokines produced by Th1 (or T cytolytic 1) and Th2 (or T cytolytic 2) cells are found in the pancreases of mice developing autoimmune diabetes. IFN-gamma is responsible for progression to diabetes, and its production is limited to lymphocytes only at that site.

Intrathymic transplantation of islet antigen affects CD8+ diabetogenic T-cells resulting in tolerance to autoimmune IDDM.

The acquisition of T-cell tolerance in the thymus is limited to those antigens expressed in the thymus at the time of T-cell development. Normally, islet antigens that are involved in insulin-dependent diabetes mellitus (IDDM) are not present in the thymus, but we have previously shown that transplantation of islets expressing relevant antigens into the thymus at the time of T-cell maturation results in prevention of IDDM in the multidose streptozotocin model of diabetes mellitus (MDSDM). Although both CD4+ and CD8+ T-cells are involved in the pathogenesis of this disease, the cells affected by intrathymic transplantation of islets are unknown. In this study, we have identified which T-cell subsets are affected by intrathymic islet antigens. Streptozotocin (STZ)-treated syngeneic islets were transplanted into the thymuses of C57BL/KsJ mice, and CD4+, CD8+, or both subsets of cells were transiently depleted with monoclonal antibodies (mAbs). After T-cell repopulation, animals that had received intrathymic islets followed by anti-CD8 mAb (P < 0.05) or both anti-CD4 and anti-CD8 mAbs (P < 0.01) but not anti-CD4 mAb alone were resistant to the development of autoimmune diabetes after five low doses of STZ. Insulitis was also reduced in mice receiving intrathymic islets and anti-CD8 (P < 0.025) or both anti-CD4 and anti-CD8 mAbs (P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Alterations in the patterns of insulin secretion before and after diagnosis of IDDM.

OBJECTIVE: To study the natural history of beta-cell dysfunction in an individual who developed insulin-dependent diabetes mellitus (IDDM) over a 13-month period while under observation. RESEARCH DESIGN AND METHODS: Insulin secretion rates (ISR) in response to intravenous glucose and mixed meals were estimated by deconvolution of C-peptide levels. RESULTS: When fasting glucose and glycosylated hemoglobin concentrations were still within the normal range, insulin secretory responses to intravenous glucose infusion were reduced, but 80- to 100-min secretory oscillations could still be detected. Sequential glucose infusion studies over a 3-month period demonstrated a progressive reduction in insulin secretion. The tight temporal coupling between ultradian oscillations in ISR and glucose observed in nondiabetic subjects was lost. In response to mixed meals, the oscillatory pattern of secretion was preserved, but the magnitude of the secretory responses was reduced. CONCLUSIONS: Our results indicate that despite the lower absolute secretory rates, ultradian ISR oscillations persist in the period before and immediately after the onset of IDDM in this subject, but they are less tightly coupled to glucose than in nondiabetic subjects.

Differential effects of anti-B7-1 and anti-B7-2 monoclonal antibody treatment on the development of diabetes in the nonobese diabetic mouse.

Insulin-dependent diabetes mellitus (IDDM) is thought to be an immunologically mediated disease resulting in the complete destruction of the insulin-producing islets of Langerhans. It has become increasingly clear that autoreactive T cells play a major role in the development and progression of this disease. In this study, we examined the role of the CD28/B7 costimulation pathway in the development and progression of autoimmune diabetes in the nonobese diabetic (NOD) mouse model. Female NOD mice treated at the onset of insulitis (2-4 wk of age) with CTLA4Ig immunoglobulin (Ig) (a soluble CD28 antagonist) or a monoclonal antibody (mAb) specific for B7-2 (a CD28 ligand) did not develop diabetes. However, neither of these treatments altered the disease process when administered late, at > 10 wk of age. Histological examination of islets from the various treatment groups showed that while CTLA4Ig and anti-B7-2 mAb treatment blocked the development of diabetes, these reagents had little effect on the development or severity of insulitis. Together these results suggest that blockade of costimulatory signals by CTLA4Ig or anti-B7-2 acts early in disease development, after insulitis but before the onset of frank diabetes. NOD mice were also treated with mAbs to another CD28 ligand, B7-1. In contrast to the previous results, the anti-B7-1 treatment significantly accelerated the development of disease in female mice and, most interestingly, induced diabetes in normally resistant male mice. A combination of anti-B7-1 and anti-B7-2 mAbs also resulted in an accelerated onset of diabetes, similar to that observed with anti-B7-1 mAb treatment alone, suggesting that anti-B7-1 mAb's effect was dominant. Furthermore, treatment with anti-B7-1 mAbs resulted in a more rapid and severe infiltrate. Finally, T cells isolated from the pancreas of these anti-B7-1-treated animals exhibited a more activated phenotype than T cells isolated from any of the other treatment groups. These studies demonstrate that costimulatory signals play an important role in the autoimmune process, and that different members of the B7 family have distinct regulatory functions during the development of autoimmune diabetes.

Diabetes induced with low doses of streptozotocin is mediated by V beta 8.2+ T-cells.

T-cells have been shown to cause insulitis and ultimately be responsible for the destruction of beta-cells in animal models of insulin-dependent diabetes mellitus (IDDM). In one murine model, insulitis and hyperglycemia occur after administration of five low doses of streptozotocin (STZ) (multidose STZ-induced diabetes mellitus [MDSM]). Insulitis can first be identified in the islets after the final (fifth) daily dose of STZ is given. We have studied the T-cells that infiltrate the islets of Langerhans during the early stages of diabetes by preparing Southern blots of T-cell receptor (TCR) beta-chain genes amplified by polymerase chain reaction (PCR) from islets from C57BL/KsJ mice given multiple doses of STZ. The relative abundance of TCR gene products in islets was compared with spleen cells stimulated with anti-CD3 monoclonal antibody (mAb). We found that after the fourth dose of STZ, there was a striking increase in the amount of V beta 8.2 TCR gene product (37 +/- 4% of total PCR signal) compared with T-cells in the spleen (9 +/- 2%, P < 0.01), which increased further 2 days after the final dose of STZ (47 +/- 5%, P < 0.001). We studied the heterogeneity of the size of the V beta 8.2 TCR CDR3 region and found primarily products with only two lengths compared with a heterogeneous population in the spleen. Treatment with anti-V beta 8 mAb, but not anti-V beta 9 and anti-V beta 13 mAbs, prevented development of hyperglycemia (P < 0.0001) and insulitis (P < 0.0005) after STZ administration.(ABSTRACT TRUNCATED AT 250 WORDS)

Prevention of autoimmune diabetes by treatment with anti-LFA-1 and anti-ICAM-1 monoclonal antibodies.

Insulin-dependent diabetes mellitus (IDDM) in humans and mouse models is caused by a T cell-mediated destruction of the beta cells in the islets of Langerhans. The interaction between T cells and their antigens or targets is assisted by adhesion molecules on the surfaces of lymphocytes and counterreceptors on antigen-presenting or other cells. One such pair of molecules thought to be of importance in IDDM is lymphocyte function-related antigen-1 (LFA-1) and intercellular adhesion molecule-1 (ICAM-1) because culture of islet cells with cytokines results in the expression of ICAM-1 on islet cells in vitro. To understand the importance of this interaction in the development of autoimmune diabetes, we have studied the ability of monoclonal antibodies (mAbs) against LFA-1 and/or ICAM-1 to prevent disease in multidose streptozotocin-induced diabetes mellitus (MDSDM). Treatment with both anti-LFA-1 and anti-ICAM-1 mAbs reduced the development of hyperglycemia and insulitis in this model. Treatment with the anti-LFA-1 and anti-ICAM-1 mAbs caused modulation of LFA-1 and ICAM-1 expression on splenocytes, respectively. In mice that were undergoing streptozotocin-induced diabetes, ICAM-1 was found on capillary endothelial cells and on cells surrounding the islets but was not expressed at detectable levels on islet endocrine cells. Thus, interaction between ICAM-1 and LFA-1 is involved in the development of autoimmune diabetes in MDSDM. It is unlikely that ICAM-1 molecules mediate adherence between T cells and islet cells themselves. Our results suggest that treatment with anti-ICAM-1 and anti-LFA-1 mAbs prevents localization of T cells to the islets rather than causing functional impairments of the lymphocytes. The actual sites of interaction between the T cells involved in MDSDM and ICAM-1 are unknown, but may occur on cells that normally express ICAM-1 in the islet or may occur outside the islet itself.